Novak Djokovic resisted a stiff first-set challenge from Benjamin Becker to ultimately ease through to the third round of the US Open in less than two hours.

The world number one faced two set points against Becker but the German could not take advantage and Djokovic prevailed 7-6 (7/2) 6-2 6-2 in an hour and 51 minutes.

The match went with serve before a double fault brought up break point for Becker in the ninth game and the Serb went long to give his opponent the chance to serve for the first set.

Djokovic moved to break point but he failed to convert and instead faced two set points - the first Becker netted following a fierce return from the Serb and then he inexplicably fired wide after moving his opponent around.

It was Djokovic's turn to move to break point again, this time taking advantage as a backhand return by Becker just failed to clear the net.

Becker levelled to send the set into a tie-break which - in contrast to what went before - was dominated by Djokovic who won 7-2.

Djokovic broke in the first game of the second set before holding for 2-0 as he found his rhythm to move into a 5-2 lead, serving out for 6-2.

The pair held serve until the fifth game of the third, when a superb backhand saw Djokovic move into a 3-2 lead with the end in sight and eventually he served out to love.